Just curious have you ever tried throwing on of these grappling dummies? Because although a bag is ok, the dummy is the closest thing to the real thing, you don't have to modify your technique very much. For example when I do the fireman's carry I reach through the legs very deep so when I pick them up I am right under them. Not to mention you can do leg picks on a legged dummy and go straight into some leg locks (no ankles), exactly the way you'd do it for real.
When I got this DVD, I was able to do all the throws on the dummy (except the scissors).
I suppose the UFC bag is a step up but I didn't hear that much good feedback on those from the jiu-jitsu forums.
The main criticism I hear about the dummy is the money, which I understand because I had to save up for a long time for this one but when you really break it down the price of a grappling dummy is about the same as an unlimited pass at an MMA gym for two months, but in this case you only pay once.
Again just my 2 cents, I'm not selling grappling dummies. If a bag works for you that's cool.
But if you are interested in buying one give me a call at my office 1-800-DUM-MMIES!
Where I'll get you a hell of a deal. 
